Forests

Adaptation

Forest management activities that increase the resilience of U.S. forests to climate change are being implemented, with a broad range of adaptation options for different resources, including applications in planning. The future pace of adaptation will depend on how effectively social, organizational, and economic conditions support implementation.

Decisions about how to address climate change in the context of forest management need to be informed by a better understanding of the risks of potential climate change effects on natural resources and the organizations that manage those resources. For example, risks posed by ecological disturbances can be reduced by first assessing specific disturbance components (such as wildfire exposure) and second identifying forest management activities that can be implemented to reduce risk.52 However, identifying how climate change will alter biophysical conditions (risk assessment) and how forest management organizations will respond to future changes (risk management) is complex. Describing operational (technical and financial), economic, and political risks is even more difficult. Furthermore, identifying interactions among all types of risks at regional and local scales will provide land managers with the information needed to manage forests sustainably across large landscapes (Ch. 28: Adaptation).137 To that end, recent nationwide projects examining site-specific adaptation practices help inform forest management focused on maintaining long-term productivity under future climatic conditions.20,138,139

Figure 6.7: Climate Change Vulnerabilities and Adaptation Options

Infographic displays four example climate change vulnerabilities for forest ecosystems in the Pacific Northwest and adaptation options for each. For example, the increasing fire season length and area burned can be addressed by reducing hazardous fuels with prescribed burning and managed wildfire. Increasing drought severity and incidence of insect outbreaks can be addressed by reducing forest stand density to increase tree vigor and by planting drought-tolerant species and genotypes. The issues of reduced snowpack, increasing precipitation intensity, and higher winter peak flows can be addressed by implementing designs for forest road systems that consider an increased flooding hazard. In addition, lower summer streamflows and increasing stream temperatures can be addressed by using mapping of projected stream temperatures to set priorities for riparian restoration and coldwater fish conservation.

Figure 6.7: To increase resilience to future stressors and disturbances, examples of adaptation options (risk management) have been developed in response to climate change vulnerabilities in forest ecosystems (risk assessment) in the Pacific Northwest. Vulnerabilities and adaptation options vary among different forest ecosystems. Sources: U.S. Forest Service and University of Washington.

Assessments of climate change effects and adaptation actions are being incorporated into resource management plans, environmental assessments, and monitoring programs of public agencies.42,140 Adaptation planning tools and compendia of adaptation options for forest resources are now institutionalized in public land management in much of the United States (Ch. 28: Adaptation).19,141 Adaptation actions are also being implemented by Native American tribes and communities, with an emphasis on culturally significant forest resources, such as flora and fauna, which in turn affect sovereignty and economic sustainability.142 Adaptation is especially urgent for Native American communities affiliated with reservations where place-based traditional medicine, ceremonial practices, and methods of gathering and hunting for food contribute to cultural identity (Ch. 15: Tribes).143

Implementing climate change adaptation measures in forest management requires an understanding of the effects of climate change on different types of forests, forest-related enterprises, and resource-dependent communities (Figure 6.7). However, even if the potential magnitude and consequences of climate change are well understood and viable management responses exist, adaptation measures cannot occur unless management organizations (on public and private lands) have the capacity (people and financial resources, enabled by policy) to implement management responses.144

Fortunately, many ongoing practices that address existing forest management needs—stand density management, surface fuel reduction, control of invasive species, and aquatic habitat restoration—contribute to the goal of increasing resilience to higher temperatures, drought, and disturbances.127,144,145,146,147 Fuel treatments across large landscapes have the additional benefit of creating defensible space for fire suppression, especially near the wildland–urban interface. Resource managers are evaluating how these practices can be modified and implemented to address future climate risks.141 For example, forest managers in dry western U.S. forests are considering greater reductions in stand density to increase forest resistance and resilience to fire, insects, and drought.148 Implementation of these practices can be costly, often confront legal and administrative barriers,149 and must consider economic tradeoffs associated with management of other natural resources.55

Reintroducing Beavers to Build Climate Resilience

Figure 6.8: Engineering by beavers encourages the slow release of water to downstream users and keeps water cool …

Applications of these and other practices vary as a function of ownership objectives, timber and non-timber wood product markets, policy constraints, and setting (urban, rural, or wildland–urban interface). For example, land managers in regions where short-rotation, plantation management of forest tree species is common (for example, private lands in the southern United States and Pacific Northwest) have the flexibility to periodically shift species and genetic composition of trees to align with future changes in climate and disturbance regimes.150 A significant amount of adaptation has occurred on public lands, including actions that reduce climate-related risks to water resources such as 1) design of sustainable forest road systems that take into account increased flooding hazard, including upsizing culverts to match projected streamflows; 2) joint planning and design of fuel treatments (including prescribed burning) and watershed restoration to create resilient terrestrial and aquatic ecosystems;127 3) comprehensive mapping of projected stream temperatures to set priorities for riparian restoration and coldwater fish conservation;151 and 4) supporting viable American beaver populations to facilitate retention of cool water in forested aquatic systems (Figure 6.8).140

Applying climate change adaptation management activities over large areas of forestland will be challenged by projected declines in the size of the forest sector workforce and receding timber product outputs in some parts of the country.42 Declines in the workforce mean fewer skilled workers who can carry out management actions, although collaborative efforts by nongovernmental organizations are emerging to assist with climate change adaptation.152 Low timber product output, the result of abundant supplies of timber and low demand for primary and secondary timber products,153 means lower prices for timber, which have trended downward since the late 1990s (e.g., Timber Mart-South 2018154), thereby providing fewer opportunities to offset treatment costs with sales of timber removed. As a result, weak timber markets mean reduced incentives for private forest owners to actively manage forests in ways that enhance climate resilience. However, multiorganization collaboration, widespread availability of adaptation options,155,156 and a growing list of examples of on-the-ground implementation bode well for the future of climate-informed forest management. Flexible management approaches that promote learning and sharing among interested parties can help accelerate implementation.